I like sticking up laminated documents next to my bench/assembly table with useful information that I need on a regular basis. In the first picture you can see a range of these documents. These pictures were actually taken quite some time ago, which means that the documents has since multiplied a smidgen, but you can get the idea.
The closeup picture show a chart with the various different clearance hole and pilot hole diameters for screw sizes 3 to 12 and a chart with the different speed settings recommended for my Festool TS55 circular saw depending on the material being cut. Below those (on the first picture) you can see three different conversion charts to help me to quickly convert imperial measurements to metric. The one that looks a bit like a ruler is by far the most useful, as it has all those confusion fractions like 7/16″ or 3/8″ or 15/32″ on one side of the ruler and you simply read off the metric equivalent on the other.
I found an excellent article on design entitled “A guide to good design” by Graham Blackburn in Fine Woodworking Magazine (January/February 2004) explaining how to use Phi (φ), the Golden Ratio and a Fibonacci Series to design objects with pleasing proportions. I made up a document with all the most pertinent bits of information, added a few drawings of my own, laminated it, and stuck it on the wall for easy access.
3/10/2013 – Since I wrote this post I have added a few things. As you can see there are two showing the different angles used when sharpening a rip vs crosscut handsaw, a chart showing the different files that should be used for the fore mentioned, and an illustration giving some guidance as to the various cambers used for different types of hand plane irons.